One of the most unexpected and emotionally complex aspects of donor conception is the reality that a single donor may have helped create dozens — sometimes hundreds — of children. These donor-conceived half-siblings, often called “diblings” in the donor conception community, share genetic heritage even when raised in entirely separate families. As DNA testing and online registries make these connections easier than ever to find, families are navigating a new frontier of extended, non-traditional kinship.
How Many Donor Siblings Are There?
The United States has no federal cap on the number of families a single sperm donor can help create, unlike countries such as the UK (which limits donations to 10 families), Denmark, and the Netherlands. Some popular U.S. sperm donors have reportedly been used by 150 or more families, meaning a single donor-conceived child may have scores of half-siblings. The Donor Sibling Registry (DSR), founded in 2000 by Wendy Kramer and her donor-conceived son Ryan, has facilitated over 23,000 matches between donor-conceived individuals and their half-siblings or donors.
Sperm banks are not required to track or report the total number of families using each donor, though the American Society for Reproductive Medicine (ASRM) recommends limiting use to 25 families per 800,000 population to minimize the risk of accidental consanguinity (unknowing relationships between half-siblings). The lack of mandatory tracking means that parents may not know how many half-siblings their child has unless they actively search through registries or DNA databases.
Finding and Connecting with Donor Siblings
The Donor Sibling Registry is the primary platform for connecting donor-conceived individuals and their families. Users can register with their donor number (assigned by the sperm bank) and be matched with other families using the same donor. Many sperm banks now offer their own family connection forums, though these are typically only accessible to clients of that bank. Consumer DNA testing services like 23andMe and AncestryDNA have become powerful tools for finding donor siblings and, in some cases, identifying previously anonymous donors.
Parents should consider proactively registering on the DSR even if they are not immediately seeking contact, as this creates the possibility for donor-conceived children to find their half-siblings when they are ready. Many families report that donor sibling connections range from annual holiday cards to deep, ongoing relationships — and everything in between. There is no “right” level of connection; what matters is that the child’s curiosity and desire for connection is honored rather than suppressed.
The Emotional Landscape of Donor Sibling Relationships
Meeting donor siblings can be a profoundly meaningful experience for donor-conceived individuals, offering a unique sense of genetic connection and shared identity. However, it can also be complicated: a child may meet a half-sibling whose family structure, values, or circumstances are very different from their own. Parents play a critical role in framing these relationships positively, neither over-investing in them (treating them like full siblings from the start) nor dismissing their significance. Donor sibling relationships exist in a category of their own — neither strangers nor traditional family — and need space to develop organically.
Research published in the journal Family Relations has found that parents who embrace donor sibling relationships tend to raise children with a more positive sense of donor conception identity. Children who have met their donor siblings report feeling less alone in their experience of being donor-conceived and often describe a sense of “recognizing” each other that they don’t feel with unrelated peers. These connections can become a meaningful part of a child’s extended family network.
Setting Healthy Boundaries in Donor Sibling Networks
When a donor has many offspring families, the logistics of maintaining multiple donor sibling relationships can become complex. Some families find themselves part of large WhatsApp or Facebook groups with dozens of other families, which can feel overwhelming or emotionally charged. It is entirely appropriate to set boundaries around the depth and frequency of contact, to prioritize relationships that feel genuinely meaningful, and to step back from group dynamics that feel unhealthy. Children’s preferences about how much contact they want with donor siblings should be respected and centered in these decisions.
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Further reading across our network: MakeAmom.com · ModernFamilyBlog.com
This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before making decisions about your fertility care.